Using an Aspect Ratio Fitter causes my Scene to be marked as dirty

The root canvas in my Scene has an Aspect Ratio Fitter added onto it, which is causing my Scene to be marked as dirty.

Cause

The Scene becomes dirty because of the canvas wanting to set the size of its RectTransform. Due to the Aspect Ratio Fitter also changing the size during the initialization, the Scene becomes dirty and leads to an unsaved change.

Resolution

You can still use the Aspect Ratio Fitter but need to place a new, empty GameObject below the canvas group. Moving the Aspect Ratio Fitter from the root canvas group to the new, empty GameObject will stop the Scene from being marked as dirty.